scholarly journals An Innovative Approach for Restoring the Mechanical Properties of Thermoplastic-Matrix Nanocomposite by the Use of Partially Polymerized Cyclic Butylene Terephthalate

2020 ◽  
Vol 4 (4) ◽  
pp. 146
Author(s):  
Francesca Ferrari ◽  
Antonio Greco
Keyword(s):  
Mechanical Properties ◽  
Healing Process ◽  
Self Healing ◽  
Butylene Terephthalate ◽  
Thermoplastic Matrix ◽  
Damaged Zone ◽  
Cyclic Butylene Terephthalate ◽  
Flexural Tests ◽  
Activation Times ◽  
Matrix Nanocomposite

This work is focused on the production of a smart material from cyclic butylene-terephthalate (CBT), characterized by the built-in capability to recover its damage, through the catalyzed ring opening polymerization (ROP) of its oligomers; in particular, molten CBT, after filling the damaged zone, can be converted into poly-butylene terephthalate (PBT), thus promoting a join of the broken surfaces and fixing the crack. To obtain a material with self-healing potential, the production of a partially polymerized system is required. For this purpose, two solutions were studied: the first one involved the use of two catalysts with different activation times, whereas the second solution implied the intercalation of the faster catalyst inside the nanoclay lamellae. Since the intercalation allowed slowing the activation of the catalyst, residual CBT can be converted in a second step. Mechanical properties of partially reacted PBT samples and their healing ability were checked by flexural analyses; in order to promote the healing process, samples were notched to simulate partial damage and left in oven for different times and temperatures, to allow the activation of the unreacted catalyst with the consequent ROP of the residual CBT; flexural tests on samples after healing showed a good recovery of mechanical properties.

Electrical and Mechanical Properties of Short-Carbon-Fiber Reinforced Polymerized Cyclic Butylene Terephthalate Composites

2015 ◽  
Vol 813 ◽  
pp. 278-284
Author(s):  
Bin Yang ◽  
Ji Feng Zhang ◽  
Lu Zhang ◽  
Shao Hua Fan ◽  
Li Min Zhou
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Percolation Threshold ◽  
Bending Test ◽  
Material System ◽  
Melt Mixing ◽  
Butylene Terephthalate ◽  
Short Carbon Fiber ◽  
Cyclic Butylene Terephthalate ◽  
Short Carbon

Polymerized cyclic butylene terephthalate (pCBT) resin casts filled with short carbon fibers were prepared by the melt-mixing approach. The electrical conductivity of short-carbon-fiber (SCF) reinforced thermoplastic pCBT resin casts were investigated with a special attention paid to the properties in the percolation threshold region and the mechanical properties of the composites were also studied. The percolation threshold value of the novel material system was determined which was also verified by SEM images and the thermoelectric behavior of the specimens. Even though the electrical properties of SCF/pCBT composites enhanced significantly, the material becomes more brittle than neat pCBT and all the specimens appear brittle fracture during the mechanical test. Moreover, fiber pull-out is the main damage form in three-point-bending test.

Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete

2016 ◽  
Vol 1813 ◽  
Author(s):  
L. E. Rendon Diaz Miron ◽  
M. E. Lara Magaña
Keyword(s):  
Mechanical Properties ◽  
Crack Formation ◽  
Healing Process ◽  
Self Healing ◽  
Reaction Products ◽  
Calcium Carbonate Precipitation ◽  
Broad Perspective ◽  
Healing Efficiency ◽  
Tensile Forces ◽  
Solubility Ratio

ABSTRACTTensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.

scholarly journals Mechanical Properties Assessment of Low-Content Capsule-Based Self-Healing Structural Composites

2020 ◽  
Vol 10 (17) ◽  
pp. 5739
Author(s):  
Xenia Tsilimigkra ◽  
Dimitrios Bekas ◽  
Maria Kosarli ◽  
Stavros Tsantzalis ◽  
Alkiviadis Paipetis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Urea Formaldehyde ◽  
Healing Process ◽  
Experimental Results ◽  
Self Healing ◽  
Healing Efficiency ◽  
A Minor

Microcapsule-based carbon fiber reinforced composites were manufactured by wet layup, in order to assess their mechanical properties and determine their healing efficiency. Microcapsules at 10%wt. containing bisphenol-A epoxy, encapsulated in a urea formaldehyde (UF) shell, were employed with Scandium (III) Triflate (Sc (OTf)3) as the catalyst. The investigation was deployed with two main directions. The first monitored changes to the mechanical performance due to the presence of the healing agent within the composite. More precisely, a minor decrease in interlaminar fracture toughness (GIIC) (−14%), flexural strength (−12%) and modulus (−4%) compared to the reference material was reported. The second direction evaluated the healing efficiency. The experimental results showed significant recovery in fracture toughness up to 84% after the healing process, while flexural strength and modulus healing rates reached up to 14% and 23%, respectively. The Acoustic Emission technique was used to support the experimental results by the onsite monitoring.

Properties of polymerized cyclic butylene terephthalate and its composites via ring-opening polymerization

2017 ◽  
Vol 31 (2) ◽  
pp. 181-201 ◽  
Author(s):  
Chun Yan ◽  
Ling Liu ◽  
Yingdan Zhu ◽  
Haibing Xu ◽  
Dong Liu
Keyword(s):  
Mechanical Properties ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Degree Of Crystallinity ◽  
Resin Matrix ◽  
Polymerization Temperature ◽  
Butylene Terephthalate ◽  
Cyclic Butylene Terephthalate ◽  
Electron Microscopy Analysis ◽  
Interlaminar Shear

Continuous glass fiber (GF)-reinforced polymerized cyclic butylene terephthalate (pCBT) composites were prepared via vacuum-assisted resin transfer molding using butyltin tris(2-ethylhexanoate) as the catalyst. The relationship between melt viscosity and polymerization time was examined in the ring-opening polymerization of CBT resin. The effects of polymerization conditions such as catalyst content and polymerization temperature on viscosity average molar mass ( Mv), crystallization, mechanical properties, and microstructure of GF/pCBT composites were also investigated in detail. It is found that both high molecular weight and high degree of crystallinity of resin matrix can lead to high mechanical properties of composites. The composites prepared with 0.5% catalyst at 190°C show the best mechanical properties with tensile strength of 549 MPa, flexural strength of 585.2 MPa, and interlaminar shear strength of 47.1 MPa. The scanning electron microscopy analysis also demonstrates that good interfacial adhesion exists between fiber and resin, which agrees very well with experimental results.

scholarly journals Healable thermoset polymer composite embedded with stimuli-responsive fibres

2012 ◽  
Vol 9 (77) ◽  
pp. 3279-3287 ◽  
Author(s):  
Guoqiang Li ◽  
Harper Meng ◽  
Jinlian Hu
Keyword(s):  
Mechanical Properties ◽  
Human Skin ◽  
Biological Systems ◽  
Healing Process ◽  
Self Healing ◽  
Stimuli Responsive ◽  
Closed Crack ◽  
Healing Efficiency ◽  
Thermoset Polymer ◽  
Crack Interface

Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heating. Here, a stimuli-responsive fibre (SRF) with outstanding mechanical properties and supercontraction capability was fabricated for the purpose of healing macroscopic damage. The SRFs and thermoplastic particles (TPs) were incorporated into regular thermosetting epoxy for repeatedly healing macroscopic damages. The system works by mimicking self-healing of biological systems such as human skin, close (stitch) then heal, i.e. close the macroscopic crack through the thermal-induced supercontraction of the SRFs, and bond the closed crack through melting and diffusing of TPs at the crack interface. The healing efficiency determined using tapered double-cantilever beam specimens was 94 per cent. The self-healing process was reasonably repeatable.

scholarly journals Effect of Cyclic Butylene Terephthalate Oligomer on the Properties of Styrene-Butadiene and Acrylonitrile-Butadiene Rubbers

2017 ◽  
Author(s):  
István Zoltán Halász ◽  
Tamás Bárány
Keyword(s):  
Mechanical Properties ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Butylene Terephthalate ◽  
Active Filler ◽  
Oil Resistance ◽  
Acrylonitrile Butadiene Rubber ◽  
Cyclic Butylene Terephthalate ◽  
Styrene Butadiene ◽  
Positive Effect

In this work the effect of cyclic butylene terephthalate (CBT) was studied on the curing, rheological, morphological and mechanical properties of styrene butadiene rubber (SBR), oil extended styrene butadiene rubber (oSBR), acrylonitrile butadiene rubbers (NBR) with various acrylonitrile (AN) content and a carboxylated acrylonitrile butadiene rubber (XNBR). The effect of CBT on the oil resistance of the NBR and XNBR based compounds was also investigated. Viscosities of the uncured compounds were significantly decreased by CBT and it also acted as a semi-active filler, effectively reinforcing the tested rubbers, therefore it is suggested to be a bifunctional additive for tested rubbers. CBT also showed to have a positive effect on the oil resistance of NBR compounds.

scholarly journals A Heterocyclic Polyurethane with Enhanced Self-Healing Efficiency and Outstanding Recovery of Mechanical Properties

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 968
Author(s):  
Jinsil Kim ◽  
Pyong Hwa Hong ◽  
Kiwon Choi ◽  
Gyeongmin Moon ◽  
Jungsoon Kang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Healing Process ◽  
Supramolecular Network ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Healing Efficiency ◽  
Bonding Interaction ◽  
Heterocyclic Group ◽  
Polyurethane Matrix ◽  
Strong Hydrogen Bonding Interaction

A functional polyurethane based on the heterocyclic group was synthesized and its self-healing and mechanical properties were examined. To synthesize a heterocyclic polyurethane, a polyol and a heterocyclic compound with di-hydroxyl groups at both ends were blended and the blended solution was reacted with a crosslinker containing multiple isocyanate groups. The heterocyclic polyurethane demonstrates better self-healing efficiency than the conventional polyurethane with no heterocyclic groups. Furthermore, unlike the conventional self-healing materials, the heterocyclic polyurethane examined in this study shows an outstanding recovery of the mechanical properties after the self-healing process. These results are attributed to the unique supramolecular network resulting from the strong hydrogen bonding interaction between the urethane group and the heterocyclic group in the heterocyclic polyurethane matrix.

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